1. Field of the Invention
This invention relates to a deflector tool, that is to say, a tool for deflecting laterally of a borehole an item passing through a borehole. Deflector tools are used particularly for deflecting tools, lining and the like through a window which has been milled in the side of the casing of a well bore.
2. The Prior Art
A deflector tool includes a deflector face which acts to guide the item to be deflected in the correct direction. Clearly, it is important that the deflector face is correctly oriented relative to the required deflector direction. For example, if an item is to be deflected through a window already milled in a casing, it is important that the deflector face is rotationally aligned so as to direct the object in question through the window.
In some instances correct rotational alignment of the deflector tool is facilitated by the fact that a rotational reference point is fixed by a tool already present in the well bore. For example, a packer having a rotational reference groove may be positioned below the window, and if this is the case, the deflector tool can be correctly oriented using the rotational reference already present. In many cases, however, no convenient rotational reference point will be available, and under these circumstances it is necessary to rotationally align the deflector tool by suitable means, and then lock it relative to the casing so that it can perform its deflector function correctly. Locking can be effected by means of a suitable packer, but if a packer is used it must be set, possibly by means of a separate packer run, and must be retrieved after the deflector tool has been used. Deflector tools are used particularly for deflecting tools, lining and the like through a window which has been milled in the side of the casing of a well bore.
A deflector tool includes a deflector face which acts to guide the item to be deflected in the correct direction. Clearly, it is important that the deflector face is correctly oriented relative to the required deflector direction. For example, if an item is to be deflected through a window already milled in a casing it is important that the deflector face is rotationally aligned so as to direct the object in question through the window.
In some instances correct rotational alignment of the deflector tool is facilitated by the fact that a rotational reference point is fixed by a tool already present in the well bore. For example, a packer having a rotational reference groove may be positioned below the window, and if this is the case the deflector tool can be correctly oriented using the rotational reference already present. In many cases, however, no convenient rotational reference point will be available and under these
If a tie back receptacle (TBR) is present in the well the present invention enables the TBR to be used to lock the deflector tool in the required rotational position during use. The deflector tool is, however, easily removed from the well after use without disturbing the TBR.
Accordingly, one aspect of the present invention provides a deflector tool comprising a deflector face at the upper end thereof and means for selectively gripping and releasing a tie back receptable and/or a well bore casing at a location below the deflector face, the means being operable for gripping in response to engagement of the deflector tool with a tie back receptacle when in use, the deflector tool being characterized in that the gripping means comprise slips which are biased into a retracted position but which are movable to an expanded position in which they can grip the interior of the TBR and/or well bore casing to prevent rotation of the deflector tool.
In the preferred embodiment of the invention, means are provided for automatically moving the slips into engagement with the interior of the TBR and/or well bore casing as the deflector tool is run into the TBR, and for releasing the slips from the TBR and/or well casing as the deflector tool is pulled from the TBR. In the preferred embodiment of the invention the slips are formed with shoulders which engage the end face of the TBR to prevent her movement of the slips. Preferably, the deflector tool is arranged so that, when in use, the shoulders engage the TBR only after at least part of the gripping portions of the slips have entered the interior of the TBR. The body of the deflector tool defines cam surfaces which act on complementary cam surfaces provided on the slips such that the further downward movement of the deflector tool body after the slips shoulders have engaged the end of the TBR will cam the slips outward into engagement with the interior of the TBR. Alternatively, the arrangement may be such that the slips are cammed into engagement with either, both the interior of the TBR and the well bore casing, or, just the well bole casing. Furthermore, when the deflector tool is pulled the cam force will bee released and the slips can be retracted away from the interior of the TBR and/or well bore casing by the biasing means.
The invention accordingly provides a simple and automatic means for locking the deflector tool in the required angular position.
Rotation of the tool to the correct angular position can be achieved by any conventional means, for example by use of a MWD tool.
The deflector tool may be made up with a mill so that the deflector tool and mill may be run into casing together and, after setting of the deflector tool, the mill may be released to enter the casing window and effect milling thereof.
In an alternative arrangement, the slips are set within the TBR by hydraulic force transmitted from the surface to a slip actuator.